The International Energy Agency (IEA) said today that power generation from renewable sources will surpass generation by natural gas by 2016. Renewables also will generate twice as much power worldwide as nuclear energy in the same time frame.

The projection is included in the IEA’s “Medium-Term Renewable Energy Market Report,” and includes electricity generation from renewable sources like hydropower, wind, solar, geothermal and biomass. Renewables are currently the fastest growing sector of the electricity generating sector, and they are expected to account for a quarter of global power generation by 2018. That is an increase from an estimated 20% share in 2011.

A few details are worth noting. First, hydropower (mostly dams) will account for about three-quarters of renewable generation in 2016. New dams are not always welcome, and there are plenty of arguments against increasing reliance on hydropower. Hydro’s share of renewable generation drops to less than 50% by 2018.

Second, modern biomass (primarily burning wood) is expected to generate about 15% of heating demand. This does not include the traditional methods of biomass burning, such as open wood fires or charcoal and dung burning. That is a good thing because such burning is a major source of carbon emissions.

By 2018, worldwide renewable electricity capacity by renewable sources will total 2.35 million megawatts, up from 1.58 million megawatts in 2012. Worldwide renewable generation will top 6,850 terawatt-hours, up from about 4,500 terawatt-hours in 2011.